There have been proposed various amplifiers for amplifying a sweep signal to drive deflection plates of a cathode-ray-tube for an oscilloscope or similar oscillographic apparatus. However, such amplifiers have not been completely satisfactory especially in linearity because of, among many other factors, fluctuation of the power supply. For example, an oscilloscope for measuring and monitoring television signals requires an extremely linear amplifier system which is almost completely independent of the power supply, yet is required to have a wide dynamic range.